The report said that one reason for the drop could be because Māori are being picked up at ED, and during the pandemic instead of getting an x-ray and other tests they were just getting a Covid test.
"We need to ensure Māori with respiratory symptoms are appropriately investigated and diagnosed," the report said.
Lung Cancer Foundation chief executive Philip Hope said Māori faced more barriers to a timely diagnosis, including molecular testing to inform treatment options, cultural barriers and access to treatments, many which are not funded.
"A disparity crisis in lung cancer persists for Maori, although all patients diagnosed with lung cancer in New Zealand are terribly disadvantaged.
He said without screening for lung cancer, the rate being picked up by GPs was very low, especially compared to other countries.
The largest gap in new diagnoses for Māori was in June-August, two to three months after the national lockdown, the report said.
"The 'gap' seems to be closing. However, this may be driven by a plateauing of cases in the last part of 2019," they said.
The agency said it was possible Māori would be further disadvantaged during the Covid-19 pandemic, with existing barriers to diagnosis and treatment worsening.
"However, this would be expected to be seen across all cancer types, not just lung cancer."
For some district health boards, the inequity is larger. The biggest drop in lung cancer diagnoses for Maori were at Auckland DHB, which had 10 fewer cases this year compared to 2019, and Waikato which dropped by 16.
Meanwhile, Canterbury DHB diagnosed eight more Māori patients with lung cancer compared to last year.
The agency also found the inequity in diagnoses did not appear to have translated into new treatment inequities.
The rate of lung cancer surgeries and radiotherapy treatment to date was similar for Māori and Pakeha, the report said.
The agency said the need was more pressing by the risk of re-emergence of Covid-19.
"Te Aho o Te Kahu will continue to work with clinicians and Covid-19 response planners to look at how to address barriers to lung cancer diagnosis in the context of Covid-19, as well as continue broader work to improve the diagnostic pathways for Māori with lung cancer."